To-be-closed variables in the C API

lapi.h

@@ -15,10 +15,23 @@
 				"stack overflow");}
 
 #define adjustresults(L,nres) \
-    { if ((nres) == LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; }
+    { if ((nres) <= LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; }
 
 #define api_checknelems(L,n)	api_check(L, (n) < (L->top - L->ci->func), \
 				  "not enough elements in the stack")
 
 
+/*
+** To reduce the overhead of returning from C functions, the presence of
+** to-be-closed variables in these functions is coded in the CallInfo's
+** field 'nresults', in a way that functions with no to-be-closed variables
+** with zero, one, or "all" wanted results have no overhead. Functions
+** with other number of wanted results, as well as functions with
+** variables to be closed, have an extra check.
+*/
+
+#define hastocloseCfunc(n)	((n) < LUA_MULTRET)
+
+#define codeNresults(n)		(-(n) - 3)
+
 #endif